The present invention relates to a vacuum cleaner, and more particularly to a vacuum cleaner which detects a quantity of dust and visually displays the detected quantity of dust.
In the past, a vacuum cleaner has been strongly demanded for improving its functions similarly to other electrified products. It is proposed and is realized to respond to the demand for improving its functions, that a dust sensor be provided to a vacuum cleaner. Specifically, a dust sensor for detecting a quantity of suctioned dust is provided at a predetermined position of a suction path, and a detection output of the dust sensor, that is the quantity of dust, is displayed in two stages (refer to U.S. Pat. No. 4,601,082).
When the vacuum cleaner having this arrangement is employee, a quantity of dust included within air suctioned through the suction path is detected during an operating period of the vacuum cleaner, and it is displayed whether the quantity of dust is great or small (including a case in which the quantity of dust is zero).
But, dust includes dust of various shapes and sizes such as small sized particles, comparatively large sized particles, cotton dust and others. And, these various dust types vary their percentages depending upon the place to be cleaned. It is almost impossible to determine which kind of dust has the greatest percentage and how much is the greatest percentage.
Therefore, a disadvantage may arise in that the display is made to show a great quantity of dust even when the quantity of dust is small in actuality, depending upon the shape and size of the dust, for example. That is, a detection output of a dust sensor is compared with a predetermined threshold value, and the result is displayed depending upon a relationship in size between the detection output and the threshold value whether the quantity of dust is great or small, for displaying a quantity of dust by two stages. Consequently, the above disadvantage may arise.
Further, it may be thought to vary the threshold value in correspondence to a shape and size of dust, but another disadvantage arises in that an operation for varying the threshold value is needed. And, when an operator forgets the operation, the above disadvantage occurs. Furthermore, a further disadvantage arises in that an extra operation for determining plural threshold values is required, which values are to be selected by an operator.
Further, an extra power supply is needed for performing detection of a quantity of dust by a dust sensor, comparison of a detection output and a predetermined threshold value, and display based upon the comparison result. And, a dry battery is generally employed as the power supply. A yet further disadvantage arises in that the dry battery must be exchanged for a new dry battery. Furthermore, when an operator forgets to exchange the dry battery, it is impossible to perform detection and display of a quantity of dust.
The present invention was made in view of the above problems.
It is an object of the present invention to display a quantity of dust in a stageless manner from a zero condition, that is, the display is varied continuously depending upon a continuous variation of a quantity of dust.